1. Field of the Invention
The present invention relates generally to the field of liquid flow controls, and more particularly, is directed to a highly sensitive, remotely controlled, mechanical, pressure regulating valve suitable to mechanically control liquid flow without the need for end limit micro switches.
2. Discussion of the Prior Art
Control valves have long been in use to regulate the flow of liquids in pipelines for all types of fluid handling systems and installations. Such prior art liquid control valves have varied in complexity from simple, hand-operated gate valves to highly complex and sophisticated, remote, electronically controlled valves. In the case of remote control valves, it has been the common practice to employ suitable motors with motor controls wherein the opening and closing of the valve could be readily functioned by electrically controlling the motor from remote locations. It has been found that such prior art remotely controlled valves will function well enough and with sufficient accuracy when the exact quantity of liquid flow is not critical and flow sensitivity is not a prime consideration.
However, in those instances wherein exact measured quantities of liquid flow have to be reliably produced, the presently available, prior art remotely controlled valves have proved to be generally unreliable and unsatisfactory. Additionally, some of the prior art remotely controlled valves functioned too quickly and others too slowly thereby frustrating the attempts of the operator to achieve exactly the desired quantities of flow. Such precise flow control capability is especially necessary in certain chemical feed applications wherein two or more liquids must be admixed in carefully controlled quantities wherein the percentage of one chemical to the other as measured in parts per million can be reliably produced.
While the prior art remotely controlled valves could approach the predetermined mixing parameters, there still remains the need to produce a valve that can be counted upon to exactly perform as desired. Additionally, the prior art remotely controlled valves were relatively expensive in construction and required electronic limit controls at the minimum and maximum flow ends to accomplish the desired flow control conditions. Accordingly, the need remains to provide a remotely controlled valve that is sensitive throughout it's range of operation to precisely control flow characteristics in accordance with predetermined criteria and which can be relatively inexpensively produced without the need for costly electronic switches or other controls to provide automatic end limit stops.